This invention relates to production of the commercially valuable compound caprolactam.
It is known that caprolactam is produced upon heating 6-aminocaproic acid or ethyl ester thereof. A low molecular weight molecule (water, ethyl alcohol) is split out and caprolactam is formed, along with greater or lesser amounts of polymeric materials.
Japanese patent publication No. 6112/1955 (Chemical Abstracts, Volume 51, 1957 at column 17984-h) is of particular interest in connection with the present invention. In accordance with this prior art publication, a dilute solution of 6-aminocaproic acid, in methanol or ethanol, is converted by heating at 220.degree.-230.degree.C. for 2-3 hours to caprolactam in 88% of theory yield. A small amount of ester (about 1%) is also recovered. The balance is unaccounted for.